In 2016, the Metro Transit Authority (MTA) in New York banned people from bringing their pets on the subway. The only exception was for animals “enclosed in a container and carried in a manner which would not annoy other passengers”.

But New Yorkers love a loophole, and so while the MTA probably meant dogs carried in purpose-built crates, subway riders quickly got inventive with tote bags and rucksacks – pushing the law to its high-fashion limits.

On Friday, however, a man found that he couldn’t quite squeeze his dog through the loophole. He was filmed by journalist Will Sabel Courtney on the subway platform at Carroll Street in Brooklyn, arguing with a train conductor about whether he was allowed to bring his dog onboard. The dog was in a burlap sack, which the man was able to hoist over his shoulder as if it was just another New Yorker tote, but the driver felt there wasn’t enough material to call it a bag.

The conductor can be heard saying “That’s not a bag, that’s not a bag” before driving the train away.

It’s unusual for the MTA to refuse an animal in this way. As the wonderful Instagram account bagdogs documents, almost any kind of bag will do.

In June 2018, the MTA briefly attempted a more hardline approach, advising a commuter on Twitter to call 911 if they saw a dog outside a bag on the subway. Twelve hours later, following a small outcry, they quickly walked backed the policy, saying it was a mistake and passengers should only call 911 in an emergency.